/*******************************************************************************
 * Copyright 2011 Mauro Luigi Drago (drago.luigi@gmail.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.bytenose.extrautils.patterns.observer;

import com.bytenose.extrautils.annotations.NonNullable;
import com.bytenose.extrautils.base.IDisposable;

/**
 * Defines a provider for push-based notifications.
 * This interface is copied from the Microsoft .NET 4 platform.  
 * @author Mauro Luigi Drago
 *
 * @param <T> The object that provides notification information.
 */
public interface IObservable<T> {
	/**
	 * Notifies the provider that an observer is to receive notifications.
	 * @param observer the object that is to receive notifications.
	 * @return a reference to an an interface that allows observers to stop receiving
	 * 			notifications before the provider has finished sending them.
	 * @throws IllegalArgumentException 
	 * 		if some of the {@link NonNullable} arguments are null.
	 */
	@NonNullable IDisposable subscribe(@NonNullable IObserver<T> observer)
		throws IllegalArgumentException;
}
